To answer the challenge of wireless broadband technologies and maintain the leadership of the 3rd Generation Partnership Project (3GPP) networks, the 3GPP organization prepared a long term evolution (LTE) plan at the end of 2004. Directed by the LTE plan, new mobile communications network architecture is defined, where only the packet switched (PS) domain remains. The architecture is called an evolved packet system (EPS).
To enable circuit switched (CS) services in an EPS network, a prior art provides a method for processing CS services in an EPS network, which may be described as a CS fallback method.
When a mobile switching center (MSC) receives a mobile terminated (MT) service, such as a CS voice call, the MSC sends a page message to a mobility management entity (MME) and the MME pages user equipment (UE) via the EPS network. When an evolved NodeB (eNodeB) receives the page message, the eNodeB first executes a PS service handover, that is, the eNodeB hands over the ongoing PS service of the UE to the PS domain of a general packet radio service/universal mobile telecommunications system (GPRS/UMTS) network. Then, the eNodeB hands over the UE to a 2nd generation/3rd generation (2G/3G) network, that is, the UE chooses a 2G/3G cell to camp. When the UE returns a page response to the MSC in the GPRS/UMTS network, the UE completes processing of the MT service.
During research and practice of the prior art, however, the inventor finds that the prior art has at least the following weaknesses:
By using the CS fallback method in the prior art, the eNodeB executes a PS service handover immediately when receiving the page message from the MME, which results in the following problems:
1. Waste of network resources. According to the prior art, when an MT service arrives, the eNodeB hands over the PS service to the PS domain of a 2G/3G network and connects the MT service. In practice, the following case often happens: When the UE is handed over to a 2G/3G network and an MT service is connected, the user rejects the MT service because the user is unwilling or unable to answer. The base station subsystem/radio network controller (BSC/RNC) regards such MT services as services that have been completed and the BSC/RNC then hands over the PS services of the UE to the EPS network. Two PS service handovers are performed for an MT service that is not normally executed, and therefore network resources are wasted.
2. Impact on the ongoing PS service of the UE. For example, a UE is in a PS service (such as a video conference) in an EPS network when it receives a CS MT service (such as a private call). According to the prior art, the eNodeB hands over the video conference to the PS domain a 2G/3G network, but because the PS domain of the 2G/3G network does not support certain PS services in the EPS network, such as the video conference, the PS service will fail. Thus, the prior art impacts the ongoing PS services.